A state of emergency has been declared after the cyclone struck the South Pacific nation on Thursday.

The Australian Government has offered immediate humanitarian assistance to Pacific island communities affected by Cyclone Evan.

Foreign Minister Bob Carr says AusAID personnel are already on the ground in Samoa to help with emergency relief coordination, and members of the Australian Civilian Corps are on standby.

"We're the biggest aid donors to the region and we have a special responsibility for the Pacific, and our hearts go out to the people of Samoa, caught in the wake of what has been a devastating cyclone", he said.

"We're working with the government very closely on the delivery of this immediate aid and looking at what we can do subsequently when it comes to reconstruction."

Senator Carr says the government has also contacted Fiji to offer early assistance.

Travel advice

Australia's Department of Foreign Affairs said the cyclone had caused "damage to local services and infrastructure, including communications and electricity services and Faleolo International Airport".

"The Australian High Commission in Apia has closed until further notice due to storm damage," DFAT said.